Process of purifying naphthalene



' perature.

tated until an intimate mixture 1s obtained;

Patented Oct. 10, 1922.

UNITED STATES PATENT OFFWE.

DAVID E. GOULD, OF CORNWELIJS, PENNSYLVANIA, ASSIGNOR. TO THE BARRETT COMPANY, A CORPORATION OF NEW JERSEY.

PROCESS OF PU I YING NAPHTHALE'HE.

No Drawing.

To all whom it may concern:

Be it known that I, DAVID F. GOULD, a citizen of the United States, residin at Cornwells, in the county of Bucks and tate of Pennsylvania, have invented certain new and useful Improvements in Processes of Purifying Naphthalene, of which the followin is a specification.

y invention relates to improvements in the process of purifyin naphthalene. In the purification of napht lene as generally practiced, the crude material containing a considerable percentage of oily impurities is brought to a molten conditlon and run into shallow pans where it is allowed to slowly crystallize. This step inthe process is for the purpose of purifying the compound by fractional crystallization; i. e., it performs the function of allowing the compound to form well defined crystals which are more readily separated from the oily impurities in the subsequent stepsof the process, which generally consists of crushing the cold crystallized material and removing the oily impurities by centrifuging, hydraulic pressin or other means.

I have foundt at the fractional crystallization above referred to may be readily effected by more economical means than by cooling in shallow pans. I have found that when the molten crude material, at a temperature slightly above its melting point, is agitated in a tank or other suitable container with water or aqueous salt solution in which it substantially insoluble, and the whole mass slowly agltated, the solid naphthalene separates in a definite crystal-.

line form which adapts itself readily to subsequent treatment' The water can be drained from the crystals. The impurities can at a later time be removed by centrifuging or hydraulic pressure, or the slurry of crystals and water or other immiscible fluid can be separated simultaneously.

In practicing this invention, while I do not wish to limit myself to the exact procedure described below, the following may serve as an example to illustrate the invention and make it clearly understood:

Molten crude naphthalene may be intro-' duced into an agitating tank at a temperature of about 85 C. with an equal volume of water at approximately the same tem- The mixture is vigorously agi- Application filed December 15, 1920. Serial No. 480,988.

are removed as completely as possible, or-

the water may be drained ofl" first and the impurities then removed independently. This procedure has been found to produce crystalline scales of naphthalene of uniform size of the same shape and structure consisting of several individual thin crystals of naphthalene laminated one upon the other.

It is to be understood that the water may be added before the naphthalene is melted and the mixture of crude naphthalene and water then heated to melt the naphthalene, after which the mixture may be vi orously agitated and then cooled. Instead of adding cold water for cooling purposes the cooling may be permitted to take place by radiation, or cooling coils or other convement cooling means may be used.

Some of the advantages with my process are as follows:

It effects a decided economy of operation over the old method of cooling in pans, digging out, crushin and conveymg to centrifugals, in that al of the materials may be handled through pumps with no manual labor. i

The process effects further economy in the original investment in that a complete series of shallow pans with buildings for housing them can be replaced by one or two agitating tanks which need not even be protected from-the weather.

The process eliminates fire risk necessarily accompanyin the use of open pans containing inflamma le material.

claim:

1. In the process of purifying naphthalene, the steps which comprise agitatin a molten mass of the same with an unmiscible liquid, and gradually cooling the mass while agitating the same to efiect relatively slow crystallization of the naphthalene.

2-. In the process of purifying naphthaliquid in which the naphthalene and its impurities are substantially insoluble, and

gradually cooling the mass while agitating the same to effect relatively slow crystallization of the naphthalene.

3. In the process of purifying naphthalene, the steps which comprise agitatin a molten mass of the same with an nnmiscfiile liquid in which the naphthalene and its impurities are substantially insoluble, and

are substantially insoluble; and. gradually cooling the mass while agitating the same .to effect relatively slow crystallization of the naphthalene.

5. In the process of purifying naphtha- .lene, the steps which comprise agitating a molten mass oft-the same with water, at

oint of a temperature above the melti n ene and naphthalene, in whi h the naphtha its impurities are substantially insoluble,

thalene, which consists in the production of crystalline scales of naphthalene of regular slze by a itating molten naphthalene and water, an slow y cooling the mixture below the melting point of the naphthalene.

7. The process of lpurifyin naphthalene, which comprises me ting sai naphthalene, mixing therewith water, and then gradually cooling the mixture by' the addition of cold water while agitating.

8. The process of purifying naphthalene; which comprises intimately mixing naphthalene and water at about 85 C. gradually reducing the temperature to about 65 C. I while a 'tating and separating theliquid from so id material.

In testimony whereof I aflix my signature.

' DAVID F. GOULD. 

